1. Field of the Invention
The present invention relates to a liquid injection recording head which is used in a liquid injection recording method in which flying droplets of a liquid are formed by injecting the liquid, and recording is performed by using the droplets.
2. Related Background Art
In a liquid injection recording method, flying droplets of a liquid are formed by injecting the liquid from a fine discharge port, and recording is performed by causing the droplets to be reached and deposited on a recording member.
In this recording method, the temperature of the liquid is critically important, because the physical properties, e.g., surface tension and viscosity, change depending on the temperature. The amount of the liquid injected, the speed of supplying the liquid, and the like also vary due to that change. Accordingly, an arrangement is conventionally adopted such that problems will not occur due to a temperature change of the liquid resulting from a change in the temperature of the external environment and the like.
Hitherto, temperature control has in many cases been effected by heating. In order to effect better temperature control, the temperature control has been carried out by providing a recording head with a heating element and by detecting the temperature of the recording head. However, with the conventional method in which the temperature of the external surface of the recording head is detected, it is difficult to detect the temperature of the interior of the recording head speedily and accurately. Particularly in the case of a recording head of a multiorifice array type (full-line type), the temperature of the liquid in the entire recording head does not necessarily become uniform due to the accumulation of heat and the like generated by the apparatus, so that it cannot necessarily be said that optimum liquid-temperature control can be effected by temperature detection using one detection means.
Furthermore, in the case of the recording head of a full-line type, where the liquid injection recording method using thermal energy is used, there have been cases where, if the liquid is discharged continuously from all of the orifices, a temperature difference arises between the liquid in the vicinity of an end portion of the recording head and the liquid in the vicinity of a central portion thereof.
Such nonuniformity of the temperature leads to the nonuniformity of the diameter of droplets formed by discharging, the discharging speed, etc. In other words, with the conventional temperature control, it has been difficult to effect accurate liquid-temperature control. Moreover, as the length of the recording head increases as in the case of the full-line type, it becomes difficult to maintain uniformity in the temperature, with the result that a difference arises in the discharging characteristics of the liquid discharged from one recording head and, hence, in the quality of a recorded image. Therefore, it has been virtually impossible to obtain satisfactory results in meeting the demand for higher-quality recording.